Study to Evaluate the Efficacy and Safety of DS-1971a for the Treatment of Diabetic Peripheral Neuropathic Pain (DPNP)

Inclusion Criteria: * Male or female ≥ 18 years of age. * Body mass index (BMI) ≤ 40 kg/m2 at screening. * Able to give written informed consent. * Type 1 or 2 diabetes. * HbA1c ≥ 7.0% and \< 9% at screening. * On a stable anti-diabetic medication regimen (unchanged dose over the last 3 months for diabetes) prior to screening (insulin therapy is acceptable); no recent (i.e., within the previous 6 months) hospitalizations due to noncompliance or uncontrolled diabetes or introduction of new medications. * ADPS of ≥ 4 on the 11-point numeric rating scale (NRS) over the past 7 days prior to randomization (based on completion of at least 4 daily pain diaries during the 7-day baseline period prior to randomization). * Painful distal symmetrical sensorimotor polyneuropathy diagnosed for at least 6 months (positive Douleur Neuropathique 4 \[DN4\] questionnaire at screening). * Women of child bearing potential (WOCBP) must be willing to use double-barrier contraception for the entire study. * Subjects who, in the judgement of the Investigator, are likely to be compliant during the study. Exclusion Criteria: * Clinically significant unstable neurologic, psychiatric, ophthalmologic, hepatobiliary, respiratory, or hematologic illness or unstable cardiovascular disease (e.g., severe hypotension, uncontrolled cardiac arrhythmia, or myocardial infarction) or any other concurrent disease within 12 months prior to screening that in the opinion of the Investigator would interfere with study…